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Smooth Ag thin films

I have a question about the deposition of very thin (40 nm) silver films on glass, I hope you can give me some idea. I am going to deposit a film like this because I want to do some study on surface plasmons, and I think I need surface roughness < 5 nm. I will do it using thermal evaporation, and I would like to know whether it is better to choose a high or a low deposition speed and whether the glass substrate should be heated or not. I did a bibliographic search on this and the only reference that I found is "Optical characterisation of gold using surface plasmon-polaritons" R A Innes and J R Sambles, J. Phys. F: Met. Phys. 17 (1987) 277-287, which says that they used fast evaporation (60 nm/min^-1) to achieve roughness < 1 nm. Also I did a search on the newsgroup using Google groups and I think that this kind of question has not yet appeared in the ng. Could someone maybe give me some reference to read?

Thanks very much in advance, Giovanni

Reply to
John Travolta Sardus
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We don't do homework problems here.

A patent search on

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spec/plasmons and spec/"thermal evaporation" gets 16 hits. U.S. Patent 6,838,121 has data from experiments on silver films deposited by thermal evaporation in which substrate temperature was held constant while deposition rate was ramped, as well as deposition rate being held constant while substrate temperature was ramped. That should pretty much answer your homework problems. :-)

Reply to
Mark Thorson

Hi, first of all, thanks very much for the answer. It had never crossed my mind to do a search on published patents. As a note, it was not a homework problem. You could be surprised that a person who is doing research on surface plasmons does not know how to deposit a thin Ag film, but well, this is my case, for the moment - I need to acquire a little bit of experience. At any rate thanks again for the suggestion, I am going to read through U.S. patent 6,838,121; it seems that it treats things similar to the ones I am interested in (maybe in a different regime, but I still have to read it with attention).

Cheers, Giovanni

Reply to
John Travolta Sardus

I was joking about that, hence the smiley. :-)

Reply to
Mark Thorson

Ok, I was slow to understand :-) I figured out that the patent 6,838,121 is interesting to me but from a different point of view. In fact the plasmons of the patent are the ones that exist in nanoparticles or rough films. I think that the big difference is that when the film is considerably thicker than the ones examined in the patent (which more or less are no thicker than 10 nm) then the film smooths out and the "localized plasmon resonances" disappear.

G.

Reply to
John Travolta Sardus

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